Many attempts to produce a superconductive conductor by forming a superconducting layer on a base material have been proposed. For example, with regard to the provision of a superconducting wire material having a desired wire material width, there is a method in which a metallic substrate having a desired width is prepared in a first stage of the production, an intermediate layer is formed on a surface of the substrate, and a superconducting layer having satisfactory crystal orientation is formed on a surface of the intermediate layer. Further, for further decreasing the thickness of the superconducting wire material obtained, a method of cutting using a laser or a method of cutting using slit processing is employed.
For example, an example of the slit processing is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 6-68727. In the method disclosed therein, in a process of polishing a surface of a base material and forming an oxide high-temperature superconducting film on the polished surface of the base material by, for example, laser abrasion, the polished base material is cut completely through and divided into plural pieces and a superconducting film is then formed on the plural pieces, or the base material on which a superconducting film is formed is cut completely through to obtain plural superconducting wires.
Another example of the slit processing is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2007-287629. The method disclosed therein includes a step of preparing a superconducting wire material and a processing step of cutting completely through the superconducting wire material by a processing section having two cutter portions that face each other. At least two processing sections are arranged adjacent to each other in the width direction of the superconducting wire material with a gap therebetween, so as to allow a superconducting wire material to be sandwiched between the two cutter portions, wherein a contact position of one cutter portion that contacts one surface of the superconducting wire material is disposed outer side in the width direction of the superconducting wire material, than the contact position of the other cutter portion that contacts the other surface of the superconducting wire material.
Japanese Patent Application Laid-Open (JP-A) No. 2007-141688 discloses, as an example of the laser cutting, a method which includes: providing a low AC loss superconductive conductor which includes an oxide superconducting layer provided on a substrate, wherein the oxide superconducting layer is separated into plural filament conductors by plural grooves for thinning that extend along a longitudinal direction of the substrate and that are arranged in the width direction of the substrate; and forming a high-resistance oxide in the grooves for thinning.
In addition, Japanese Patent Application Laid-Open (JP-A) No. 2010-192116 discloses that a superconducting wire material has a structure in which an intermediate layer and a superconducting layer are sequentially formed and layered on a substrate, and covered with a protective layer. JP-A No. 2010-192116 further discloses a method for forming a slit in the substrate, and the slit satisfies requirements of 1) the slit is formed on a face of the substrate at a side opposite to the face on which the superconducting layer is formed, 2) the slit has a depth penetrating into part of the thickness of the substrate, and 3) at least one slit is present in any cross-section orthogonal to the longitudinal direction of the superconducting wire material.